如何将 Parcelable 传递给两个或多个活动或片段？

Question

我可以将Parcelable 传递给一个片段或活动，但我不能将Parcelable 传递给两个或更多片段或活动。

当我单击列表项时，我在 Fragment 中有一个 ListView，列表项详细信息将发送到 GetFragment1、GetFragment1 我有显示列表项更多详细信息的按钮，我想从 GetFragment2 和 GetFragment3 中的 SendFragment 获取 Parcelable。

这是Test.java

import android.os.Parcel;
import android.os.Parcelable;

public class Test implements Parcelable {

    private int studentNumber;
    private String studentName;
    private String studentFamily;

    public int getStudentNumber() {
        return studentNumber;
    }

    public void setStudentNumber(int studentNumber) {
        this.studentNumber = studentNumber;
    }

    public String getStudentName() {
        return studentName;
    }

    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }

    public String getStudentFamily() {
        return studentFamily;
    }

    public void setStudentFamily(String studentFamily) {
        this.studentFamily = studentFamily;
    }

    public Test() {
    }

    public Test(Parcel read) {
        studentNumber = read.readInt();
        studentName = read.readString();
        studentFamily = read.readString();
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel write, int flags) {
        write.writeInt(studentNumber);
        write.writeString(studentName);
        write.writeString(studentFamily);
    }

    public static final Parcelable.Creator<Test> CREATOR =
            new Parcelable.Creator<Test>() {
                @Override
                public Test createFromParcel(Parcel source) {
                    return new TestP(source);
                }
                @Override
                public Test[] newArray(int size) {
                    return new TestP[size];
                }
            };
}

在FragmentSend.java我想发送数据到FragmentGet1.java和FragmentGet2.java和FragmentGet3.java，这是代码：

public class FragmentSend extends ListFragment {

    //    Classes
    TestReadData readData;
    TestDataSource dataSource;

    private List<Test> listTest;       

    public FragmentSend() {
        // Required empty public constructor
    }


    @TargetApi(Build.VERSION_CODES.M)
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View layout = inflater.inflate(R.layout.fragment_send, container, false);

        readData = new TestReadData(getContext());
        dataSource = new TestDataSource(getContext());  

       refreshStudentList(inflater);

    return layout;
}

public void refreshStudentList(LayoutInflater inflater) {

    listTest = readData.getAllStudentRows();
    ArrayAdapter<Test> testAdapter = new TestFragmentListAdapter(inflater.getContext(), listTest);
    setListAdapter(testAdapter);

}

    @Override
    public void onResume() {
        super.onResume();
        dataSource.open();
    }

    @Override
    public void onPause() {
        super.onPause();
        dataSource.close();
    }

    @Override
    public void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);

        Test model = listTest.get(position);

         Bundle bundle = new Bundle();
         bundle.putParcelable("Student", model);

        FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();


    Fragment fragmentGet1 = new FragmentGet1();
    Fragment fragmentGet2 = new FragmentGet2();
    Fragment fragmentGet2 = new FragmentGet3();

    fragmentGet1.setArguments(bundle);
    fragmentGet2.setArguments(bundle);
    fragmentGet3.setArguments(bundle);



    fragmentTransaction.replace(R.id.frame_container, fragmentGet1);
    fragmentTransaction.addToBackStack(null);
    fragmentTransaction.commit();

    }

在GetFragment1.java 中，我可以成功获得Parclable，但在另外两个片段（GetFragment2.java 和GetFragment3.java）中，捆绑包将为空！

这是获取 Parcelable 的 GetFragment1.java 代码： 我将此代码用于其他两个片段。

Bundle bundle;
bundle = this.getArguments();
    if (bundle != null) {
                model = bundle.getParcelable("Student");
                if (model != null) {

                    Log.i(LOG_TAG, String.valueOf(String.valueOf(model.getStudentNumber());

                }
            } else {
                Log.i(LOG_TAG, "LogDetailsFragment 'bundle' is null!");
            }

如何发送Parcelable 以获得更多片段？

Answer 1

好的，你的问题在于事情的顺序。在这部分代码中：

Fragment fragmentGet1 = new FragmentGet1();
Fragment fragmentGet2 = new FragmentGet2();
Fragment fragmentGet2 = new FragmentGet3();

fragmentGet1.setArguments(bundle);
fragmentGet2.setArguments(bundle);
fragmentGet3.setArguments(bundle);

您正在创建所有 3 个片段的 实例，但随后仅使用 FragmentGet1 的实例。其他的不使用。稍后，当您创建任何这些 Fragments 的另一个实例时，它不会有 args，因为 它是一个完全独立的对象。

您需要在每次创建新片段时将包向前传递。如果你想从已经创建的片段中创建它，它看起来有点像这样：

public void showNextFragment() {

    FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

    Fragment fragmentGet2 = new FragmentGet2();

    if(this.getArguments() != null)
        fragmentGet2.setArguments(this.getArguments());

    fragmentTransaction.replace(R.id.frame_container, fragmentGet2);
    fragmentTransaction.addToBackStack(null);
    fragmentTransaction.commit();

}

将它放入您的 FragmentGet1 中，如果您需要的话，请告诉我 :-)

编辑： 要将 Student 对象传递给 Activity，只需执行以下操作：

    Student s = //get it here
    Bundle b = new Bundle();
    b.putParcelable("student", s);

    Intent i = new Intent(getActivity(), ThatOtherActivity.class);
    i.putExtra("extraWithStudent", b);
    startActivity(i);

然后读取Activity中的数据：

    Intent incomingIntent = getIntent();
    Bundle b = incomingIntent.getBundleExtra("extraWithStudent");
    Student s = (Student) b.getParcelable("student");